.TITLE	MPVTCB
	.IDENT	/V1.0A/
;
; WRITTEN BY R. KINNE STRONG, 14-DEC-77
;
; THIS IS A FORTRAN-CALLABLE ROUTINE THAT WILL ENABLE FORTRAN TRACEBACK
; ON A MEMORY PROTECT VIOLATION (SST 1).  THIS ROUTINE IS NECESSARY
; BECAUSE THE VERSION OF OTS SHIPPED WITH RSX1-11M FORTRAN V01C
; DOES NOT RECOVER SST 1'S SO THE OFFENDING TASK GETS ONLY THE SYSTEM
; ERROR MESSAGE, WHICH IS NOT VERY USEFUL.
;
; TO USE THIS ROUTINE, SIMPLY CALL MPVTCB SOMETIME BEFORE THE
; OFFENDING MEMORY REFERENCE.  MPVTCB MAY BE CALLED AS MANY TIMES
; AS YOU CHOOSE WITHOUT ANY HARMFUL EFFECTS.
;
; THE PC OF THE OFFENDING INSTRUCTION IS NOT PRINTED.  SORRY.  IF IT
; TURNS OUT TO BE USEFUL, YOU CAN ALWAYS TAKE OUT THE CALL AND
; RE-CREATE THE PROBLEM.  (I HOPE!)
;
; IN WRITING THIS, I RELIED ON INFORMATION IN THE FOLLOWING:
;
; IAS/RSX-11 FORTRAN IV USER'S GUIDE, SECTIONS C.2.3.2 AND C.2.4
;
; RSX-11M EXECUTIVE REFERENCE MANUAL, SECTION 2.3.2
;
MPVTCB::MOV	#MYRTN,$SST+2	;ENABLE MY SST ROUTINE
	RETURN			;GO HOME, ALREADY!

MYRTN:	ADD	#2*5,SP		;POP ALL THE DETAILS OFF THE STACK
	TRAP	128.+4		;GIVE OTS ERROR 4
	IOT			;SHOULD NOT RETURN FROM TRAP

	.END